deletions | additions       diff --git a/subsection_AC_Conductivity_If_the__.tex b/subsection_AC_Conductivity_If_the__.tex  index aa2d523..9ca324a 100644  --- a/subsection_AC_Conductivity_If_the__.tex  +++ b/subsection_AC_Conductivity_If_the__.tex 
...
\subsection{AC Conductivity}  If the applied voltage is a small pure AC signal with $V_{dc}=0$ and $|V_{ac}|  \begin{equation}  \sigma() \sigma(V_{dc})=\sigma_0+sigma_{dc}  \end{equation}